Bandwidth allocation in ethernet networks

ABSTRACT

For assigning bandwidth in a constrained topology ethernet network there is presented a function that creates and manages a ledger of bandwidth requests over the ethernet network. The function, a bandwidth manager, tracks the total bandwidth of each link in the network and the bandwidth that has been reserved on each link. When traffic is granted reserved bandwidth the bandwidth manager notes this allocation in the ledger. The header of the traffic packets indicates that the traffic is of highest priority when the traffic has been given reserved bandwidth. In this manner the bandwidth manager can track and limit the amount of high priority traffic on the network.

FIELD OF THE INVENTION

The present invention relates to the allocation of bandwidth inconstrained topology ethernet networks.

BACKGROUND OF THE INVENTION

Ethernet has become the most popular physical layer for local areanetworks and is finding a market in larger data networks (i.e.metropolitan area and wide area). The popularity of ethernet is due inpart to the good balance found between cost, speed and installation andmaintenance difficulty.

The desire to reduce operating costs in networks of all sizes hasproduced the movement towards networks that can provide multipleservices, such as carrying voice, video and data. Many of the currentsolutions to this problem have relied on ATM switching to map multipleservices onto a network. These ATM networks typically operate at speedsbetween DS-1 (1.544 kbps) to OC-48 (2.5 Gbps) but the cost resultingfrom the higher speed complex processing leads to expensive networksolutions. In addition, as traffic demands grow the evolution to fasterATM products is very costly. Further, expensive equipment is required toconnect to an ATM-based network.

While ATM cells are effective for controlling “first mile jitter”problems, they are inefficient for carrying both voice and data as thecells are too long for voice but too short for data.

The use of frame-based ethernet, especially Gigabit ethernet, as asolution for the problems encountered with data traffic using ATMswitching has been capitalized in the metropolitan area network (MAN) byproviders such as Yipes™ and Telseon™. However, current high-speedethernet-based networks only provide a single data service.

As the transmission rate for ethernet has increased to 1 Gbps and 10Gbps it becomes possible to mix real-time traffic with large data frameswithout incurring large delays since the real-time packets no longerincur a long delay waiting for the completion of the transmission of alarge data packet. For example, a 1500 byte data packet only requires1.2 microseconds on an Ethernet network where as at ATM OC-3 rates (150Mbps) an ATM cell requires a similar order of magnitude time at 2.8microsceonds.

Although ATM networks operate at slower speeds than other networks, forexample ethernet-based networks, ATM provides a guaranteed level ofservice not provided by ethernet-based networks. ATM networks offerQuality of Service (QoS) that guarantees a throughput level on thenetwork between origination and destination.

The advantage of ATM networks is that this QoS ensures that undertraffic congestion conditions some users can be guaranteed that theirtraffic will never be discarded. This characteristics makes ATMattractive for real-time applications, such as circuit emulation, whereeven small amounts of information loss can severely impact the service.Ethernet networks on the other hand are only able to assign traffic toclasses that have different traffic handling characteristics.Unfortunately, these classes do not guarantee that data within theseclasses is never discarded. If the total volume of traffic requests fora specific class exceeds the bandwidth assigned to that class trafficwill be discarded.

Further, since the path taken by packets in an ethernet network is notknown by the source and there is no switch by switch allocation ofbandwidth on trunks, an ethernet network is not able to allocatebandwidth to specific data flows.

SUMMARY OF THE INVENTION

For assigning bandwidth in a constrained topology ethernet network thereis presented a function that creates and manages a ledger of bandwidthrequests over the ethernet network. The function, a bandwidth manager,tracks the total bandwidth of each link in the network and the bandwidththat has been reserved on each link. When traffic is granted reservedbandwidth the bandwidth manager notes this allocation in the ledger. Theheader of the traffic packets indicates that the traffic is of highestpriority when the traffic has been given reserved bandwidth. In thismanner the bandwidth manager can track and limit the amount of highpriority traffic on the network.

In accordance with one aspect of the present invention there is provideda bandwidth manager for controlling bandwidth resources in an ethernetnetwork having a plurality of nodes, selected pairs of nodes beingseparated by links of predetermined link bandwidth capacities, theethernet network having a plurality of paths connecting at least two ofthe plurality of nodes together, each of said plurality of paths beingcomposed of at least one link. The bandwidth manager includes: means forreceiving a bandwidth reservation request including a requestedbandwidth capacity, an origination point and a destination point; meansfor storing available bandwidth capacity for each link in the ethernetnetwork; and means for reserving link bandwidth capacity on a selectedone of the plurality of paths based on said bandwidth reservationrequest and said available bandwidth capacity for each link in theselected one of the plurality of paths.

In accordance with another aspect of the present invention there isprovided a method of controlling bandwidth resources in an ethernetnetwork having a plurality of nodes, selected pairs of nodes beingseparated by links of predetermined link bandwidth capacities, theethernet network having a plurality of paths connecting at least two ofsaid plurality of nodes together, each of said plurality of paths beingcomposed of at least one link. The method includes the following steps:receiving a bandwidth reservation request including a requestedbandwidth capacity, an origination point and a destination point;storing available bandwidth capacity for each link in the ethernetnetwork; and reserving link bandwidth capacity on a selected one of theplurality of paths based on said bandwidth reservation request and saidavailable bandwidth capacity for each link in the selected one of theplurality of paths.

In accordance with another aspect of the present invention there isprovided a node on an ethernet network for controlling bandwidthresources, the ethernet network having a plurality of nodes, selectedpairs of nodes being separated by links of predetermined link bandwidthcapacities, a plurality of paths connecting at least two of theplurality of nodes, each of said plurality of paths being composed of atleast one link. The node comprising: a receiver accepting a bandwidthreservation request including a requested bandwidth capacity, anorigination point and a destination point; a data store containingavailable bandwidth capacity for each link in the ethernet network; anda request processor for reserving link capacity on a selected one of theplurality of paths based on said bandwidth reservation request and saidavailable bandwidth capacity for each link of the chosen one of theplurality of paths.

In accordance with another aspect of the present invention there isprovided a computer readable medium having stored thereon computerexecutable instructions for controlling bandwidth resources in anethernet network having a plurality of nodes, selected pairs of saidplurality of nodes being separated by links of predetermined linkbandwidth capacity, the ethernet network having a plurality of pathsconnecting at least two of said plurality of nodes together, each ofsaid plurality of paths being composed of at least one link. Thecomputer executable instructions comprising the steps of: receiving abandwidth reservation request including a requested bandwidth capacity,an origination point and a destination point; storing availablebandwidth capacity for each link in the ethernet network; and reservinglink bandwidth capacity for a selected one of the plurality of pathsbased on said bandwidth reservation request and said available bandwidthcapacity for each link in the chosen one of the plurality of paths.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described in conjunction with the drawingsin which:

FIG. 1 illustrates a ring topology ethernet network having bandwidthallocation capabilities according to an embodiment of the presentinvention;

FIG. 2 illustrates a star topology ethernet network having bandwidthallocation capabilities according to an embodiment of the presentinvention;

FIG. 3 illustrates a system diagram of a bandwidth manager according toan embodiment of the present invention;

FIG. 4 illustrates a flow diagram of the bandwidth manager according toan embodiment of the present invention; and

FIG. 5 illustrates a system diagram of a bandwidth allocation interfacefor an ethernet bridge according to an embodiment of the presentinvention.

DETAILED DESCRIPTION

FIG. 1 is a network architecture diagram of a ring topology ethernetnetwork 10 having bandwidth allocation capabilities according to anembodiment of the present invention. This invention enables bandwidth tobe effectively assigned in the ethernet network 10 through a combinationof a constrained topology network 10 and the use of a bandwidth manager16 that creates and manages a ledger of bandwidth requests for theethernet network 10.

Ethernet bridges 12 connect data sources 24 to the ethernet network 10.The data sources 24 may be individual data producing devices, such ascomputers, or the data sources may be other networks. The data sources24 each have interfaces (not shown) at the ethernet bridges 12connecting them and allowing them to send data between the data source24 and the ethernet bridge 12. Packets having headers that contain adata source address for the originator and a data source address for thedestination are forwarded to the ethernet bridges 12 to be sent alongthe ethernet network 10.

The ethernet bridges 12 are simple switching devices and do not containrouting functions. The ethernet bridges 12 learn what data sources 24are connected to each ethernet bridge 12 by looking at the data sourceaddress for the originator in each data packet that passes through thebridge 12 and remembering the interface the packet arrived on. Theethernet bridges 12 all have data stores (not shown) that contain alisting of the data source addresses and corresponding interfaces thatmay be used for translating data source addresses for the destinationinto an interface to which a received packet may be forwarded.

Connected within the ethernet network 10 to the ethernet bridges 12 is acore switch 18 that interfaces the ethernet network 10 with a secondnetwork (not shown). The second network to which the core switch 18 isinterfacing can be a network using a different communications protocolor physical layer than the ethernet network 10. The core switch 18examines the packets it receives and determines a destination point onthe second network. The packet can then be forwarded to its destinationpoint. The core switch 18 can also analyze the entire packet to look forerrors that would keep the packet from propagating through the secondnetwork. The core switch 18 may employ a number of switchingtechnologies, such as ATM, TDM cross-connects or MPLS switches. In allthree cases, the core switch 18 would assign bandwidth to connections inthe second network to ensure that the bandwidth requested in theethernet network 10 is provided end-to-end for the packets.

The bandwidth management for a ring topology is described in network 10.The bandwidth reservation and allocation capabilities in the network 10are found in a bandwidth manager 16 and bandwidth allocation interfaces14. The bandwidth manager 16 may be a separate component attached one ofthe switches in the network 10, or alternatively, the functions of thebandwidth manager 16 may be contained in one of the ethernet bridges 12.

The bandwidth manager 16 is the single source in the network 10 for theallocation and reservation of bandwidth. When a data source 24 connectedto one of the ethernet bridges 12 desires bandwidth reservation thebandwidth manager 16 is contacted and the request is made. The bandwidthmanager 16, once bandwidth availability for each link in the network 10has been determined, reserves the requested bandwidth. The originatingdata source 24 is informed that the bandwidth has been reserved andprepares the packet headers accordingly.

The bandwidth allocation interfaces 14 are each connected to each of theethernet bridges 12 to enable the bridges 12 to communicate with thebandwidth manager 16. The bandwidth allocation interface 14 negotiateswith the bandwidth manager 16 for bandwidth reservation. The role of thebandwidth allocation interface 14 is to accept requests for bandwidthfrom data sources 24 and to forward those requests to the bandwidthmanager 16.

For CBR (Constant Bit Rate) traffic, the packet headers have a prioritystatus indictor noting that the traffic must be forwarded at the highestpriority. Control traffic might run at a higher priority than CBR butsince control traffic has a very low volume the bandwidth manager 16includes control traffic in its highest priority allocation. To providethe required service for CBR traffic, the ethernet bridges 12 have anabsolute priority queuing mechanism (“serve to exhaustion”) for thehighest priority traffic. If the ethernet bridge 12 has a configurablebandwidth allocation mechanism, the bandwidth manager 16 mustcommunicate back to each ethernet bridge 12 to modify the bandwidth toreflect the increase (or decrease if a connection is terminated) inrequested bandwidth.

Only data sources 24 that are participating in the reservation mechanismare allowed to send packets with packet headers set to the highestpriority to ensure only registered users have access to this service.This is controlled by both the bandwidth manager 16 and the bandwidthallocation interface 14 by comparing the source address in a packetheader with a list containing those data sources 24 that have permissionto reserve bandwidth on the network 10.

The bandwidth manager 16 reserves the required bandwidth for trafficaround the network 10. This ensures that if there is a break in thenetwork 10, either due to failure of an ethernet bridge 12 or a cut inthe link between a pair of ethernet bridges 12, traffic can be forwardedin the opposite direction around the network 10 to reach the destinationwithout concern for congestion, i.e. the bandwidth is allocated to alllinks around the entire network 10. Since the network topology has beenconstrained to a ring in this case, the bandwidth can be allocatedwithout explicit knowledge for each connection by each ethernet bridge12.

In the ring topology where all traffic is destined to the core switch18, link between the ethernet bridges 12 may have different linkcapacity. For example, the links furthest away from the core switch 18may have a lower link capacity than those links closer to the coreswitch 18.

FIG. 2 is a network architecture diagram of a star topology ethernetnetwork 26 having bandwidth allocation capabilities according to anembodiment of the present invention. Ethernetmultiplexers(muxes)/bridges 12 connect and multiplex multiple datasources 24 to the network 26. Traffic from multiple data sources 24,such as individual data producing devices or networks, are multiplexedtogether at the ethernet mux/bridge 20 to be passed to an ethernetswitch 22.

Each ethernet mux 20 is aware of all the data sources 24 that aredirectly connected to that mux 20. Since the ethernet switches 22 arenot interconnected all traffic flows from originating mux 20 to oneethernet switch 22 to destination mux 20. That is, each ethernet mux 22is connected to the same ethernet switch 22 as the destination mux 20.In this constrained architecture each mux 20 operates a local instanceof a bandwidth manager 16 to ensure that there is no congestion on thelink to the ethernet switches 22 that would violate the bandwidthcontracts requested by the data sources 24. The bandwidth manager 16, asin FIG. 1 is the source for allocation and reservation of bandwidth.

Traffic enters the ethernet mux 20 from a data source 24 that isparticipating in the reservation system. The traffic is inserted into anethernet packet (e.g. circuit emulation over MPLS over ethernet) and thedestination address is the address of a port on this or another ethernetmux 20. The packet is forwarded from the mux 20 to the ethernet switch22 where the destination address is examined and the packet is thenforwarded onto the destination.

Multiple ethernet mux/bridges 20 are redundantly connected to multipleethernet switches 22. Each ethernet switch 22 is connected to the sameethernet muxes/bridges 20. That is, each ethernet mux/bridge 20 isindividually connected to each ethernet switch 22. In this manner, ifone of the ethernet switches 22 fails then the other ethernet switch 22will take over the functions of the failed switch 22.

The ethernet switches 22 are unaware of the bandwidth allocations madeby the ethernet muxes 20, making it possible for the ethernet switch 22to forward a connection request to the mux 20 that exceeds the remainingbandwidth on the link between the mux 20 and the ethernet switch 22. Inthis situation, the mux 20 will refuse the request back to the sourcemux 20. In the star topology 26, there is not a bandwidth allocationinterface since the bandwidth manager 16 is operated in the mux 20 (i.e.not centralized as in the ring topology) and therefore there is no needto communicate with a remote bandwidth manager.

The core switch 18 in the star network 26 is connected to each of theethernet routers 22. The core switch 18, as in FIG. 1, interfaces theethernet network 26 with another network. The network to which the coreswitch 18 is interfacing can be a network using a differentcommunications protocol or physical layer than the ethernet network 10.

FIG. 3 is a system diagram of a bandwidth manager 16 according to anembodiment of the present invention. Bandwidth request packets from thebandwidth allocation interfaces 14 requesting bandwidth are received atan I/O interface 40 and passed to a request processor 42. The requestprocessor 42 is responsible for coordinating bandwidth reservationrequest processing. The request processor 42 extracts the requestedbandwidth capacity from the bandwidth request packet and consults abandwidth ledger 44 to determine if there is sufficient bandwidthavailable on all links in the path to be taken by the traffic.

The bandwidth ledger 44 includes a main table 46 containing basicinformation on each of the links in the network 10, 26. The links aredefined by the two endpoints on the link. As different links may havedifferent bandwidth capacity, the total bandwidth for each link is notedwith the allocated and available bandwidth. For the bandwidth that hasbeen allocated an allocation table 48 provides details of eachreservation for the link. Allocated bandwidth has an identifier that isassigned to the source of the traffic. This allows audit to be performedto ensure that bandwidth is not assigned to a source that no longerexists. Each identifier has an associated bandwidth amount that has beenreserved and an associated priority level.

The bandwidth manager 16 may keep separate ledgers for differentservices such as CBR (Constant Bit Rate) and VBR (Variable Bit Rate).For CBR requests, the bandwidth manager 16 must ensure that the fullbandwidth request is allocated to the requester since CBR guaranteesthat the sender can send at the requested rate with absolutely no lossof information. For VBR traffic, the bandwidth manager 16 may choose toallocate more bandwidth than is available since for VBR as the user isnot given an absolute guarantee but a probability that they can send atthe requested rate.

The request processor 42 has a bandwidth ledger interface 50 and abooking manager 52. The bandwidth ledger interface 50 provides therequest processor 42 with an interface to the bandwidth ledger 44. Thebandwidth ledger interface 50 enables the request processor 42 to accessthe tables 46, 48 containing bandwidth capacity information. Theinformation accessed by the bandwidth ledger interface 50 allows therequest processor 42 to determine if there is enough bandwidth capacityof the links between the origination and destination points to completea received bandwidth reservation request. The booking manager 52receives an indication that there is sufficient bandwidth and reservescapacity on each link between the destination and origination points asindicated in a bandwidth reservation request.

The bandwidth manager 16 also contains a registered data sources table50 that lists all data sources 24 that are registered to use thebandwidth reservation offered by the bandwidth manager 16. Uponreceiving a request for bandwidth reservation, the request processor 42consults the data sources table 50 to ensure the data source 24requesting the bandwidth reservation is registered to use the service.

FIG. 4 is a flow diagram of the bandwidth manager 16 according to anembodiment of the present invention. At initialization the bandwidthmanager 16 would clear the bandwidth ledger 44 of allocated bandwidth tozero for all links in step 62. A request for bandwidth reservation isreceived in step 64 at the bandwidth manager 16 from the bandwidthallocation interface 14. The request contains the originator address,the priority level of the traffic and the amount of bandwidth requested.The information contained in the request is extracted in step 66. Thebandwidth manager 16 checks to confirm that the requesting data source24 is registered to reserve bandwidth in step 68. If the requesting datasource 24 is not registered then the bandwidth allocation interface 14that sent the request is informed that the request could not becompleted in step 76.

Based on the path through the network the traffic will follow thebandwidth manager 16 checks each link for the available bandwidth instep 70. The path will be dependant on the topology of the network. Forexample, in a ring configuration the path is considered to be the entirering network so bandwidth on every link in the network must be reserved.In a star configuration only bandwidth on those links between originatorand destination ethernet muxes and a connecting ethernet switch needs tobe reserved. The available bandwidth is compared in step 72 to therequest for bandwidth to ensure there is sufficient available bandwidthfor the requested reservation. If there is insufficient bandwidth on atleast one of the links in the path then the bandwidth allocationinterface 14 is informed in step 76 that the request for bandwidthreservation cannot be completed.

If there is sufficient bandwidth available on all links then thebandwidth manager 16 reserves the requested bandwidth for all links inthe path in step 74. This is accomplished by adding an entry to theallocation table 48 of each link in the route. Each new entry in eachallocation table 48 for each link will contain identical information(i.e. originator address, bandwidth allocated and priority level oftraffic).

FIG. 5 is a system diagram of a bandwidth allocation interface 14 for anethernet bridge according to an embodiment of the present invention. AnI/O interface 80 connects the bandwidth allocation interface 14 with theethernet bridge 12. The I/O interface 80 sends messages to the bandwidthmanager 16 requesting a reservation of bandwidth.

The bandwidth reservation requests are prepared by a message packager 82connected to the I/O interface 80. The message packager 82 receivesinformation from a bandwidth calculator module 84, a priority levelmodule 86 and a destination module 88. The information received fromthese modules 84, 86, 88 is the basis for the bandwidth reservationrequest.

The bandwidth allocation interface 14 contains a registered data sourcetable 90 having a list of all data sources 24 connected to the ethernetbridge 12 of the bandwidth allocation interface 14 that are registeredto reserve bandwidth. The message packager 82 consults the registereddata source table 90 to determine if a bandwidth reservation requestshould be forwarded based on whether or not the originator is listed asbeing registered to reserve bandwidth.

The bandwidth calculator module 84, the priority level module 86 and thedestination module 88 extract data from traffic coming into the ethernetbridge 12 that is destined for the network 10. The destination module 88examines all traffic coming into the ethernet bridge 12 to determine itsdestination point. If the detected destination point is accessible bythe network 10 then the destination module 88 extracts the destinationpoint from the traffic and forwards this information to the messagepackager 82. This causes the priority level module 86 to be invoked todetermine the traffic type. Based on the traffic type the priority levelmodule 86 can determine whether or not bandwidth needs to be reserved.If the traffic is time-sensitive, such as voice, then the priority levelmodule 86 informs the bandwidth calculator module 84 that bandwidth mustbe reserved. The priority level module 86 passes the priority level ofthe traffic to the message packager 82. The bandwidth calculator module84 determines the amount of bandwidth that needs to be requested andforwards this to the message packager 82. Upon receipt of the bandwidthamount the message packager 82 creates a request for bandwidth that istransmitted to the bandwidth manager 16.

It is apparent to one skilled in the art that numerous modifications anddepartures from the specific embodiments described herein may be madewithout departing from the spirit and scope of the invention.

1. A bandwidth manager for controlling bandwidth resources in anethernet network having a plurality of nodes, selected pairs of nodesbeing separated by links of predetermined link bandwidth capacities, theethernet network having a plurality of paths connecting at least two ofthe plurality of nodes together, each of said plurality of paths beingcomposed of at least one link, said bandwidth manager comprising: meansfor receiving a bandwidth reservation request including a requestedbandwidth capacity, an origination point and a destination point; meansfor storing available bandwidth capacity for each link in the ethernetnetwork; and means for reserving link bandwidth capacity on a selectedone of the plurality of paths based on said bandwidth reservationrequest and said available bandwidth capacity for each link in theselected one of the plurality of paths.
 2. The bandwidth manager ofclaim 1 wherein said means for reserving link bandwidth capacityincludes: means for consulting said means for storing to determine ifthe bandwidth capacity available for all links in the selected one ofthe plurality of paths is greater than the requested bandwidth capacity;and means for reserving bandwidth for the links of the selected one ofthe plurality of paths if the bandwidth reservation request can besatisfied for all links in the selected one of the plurality of paths.3. The bandwidth manager of claim 1 further including means fordetermining the selected one of the plurality of paths based on theorigination point and the destination point in the bandwidth reservationrequest.
 4. A method of controlling bandwidth resources in an ethernetnetwork having a plurality of nodes, selected pairs of nodes beingseparated by links of predetermined link bandwidth capacities, theethernet network having a plurality of paths connecting at least two ofsaid plurality of nodes together, each of said plurality of paths beingcomposed of at least one link, said method comprising the steps of:receiving a bandwidth reservation request including a requestedbandwidth capacity, an origination point and a destination point;storing available bandwidth capacity for each link in the ethernetnetwork; and reserving link bandwidth capacity on a selected one of theplurality of paths based on said bandwidth reservation request and saidavailable bandwidth capacity for each link in the selected one of theplurality of paths.
 5. The method of claim 4 wherein said step ofreserving link bandwidth capacity includes the steps of: consulting thestored bandwidth information to determine if the bandwidth capacityavailable for all links in the selected one of the plurality of paths isgreater than the requested bandwidth capacity; and reserving bandwidthfor the links of the selected one of the plurality of paths if thebandwidth reservation request can be satisfied for all links in theselected one of the plurality of paths.
 6. The method of claim 1 furtherincluding the step of determining the selected one of the plurality ofpaths based on the origination point and the destination point in thebandwidth reservation request.
 7. A node on an ethernet network forcontrolling bandwidth resources, the ethernet network having a pluralityof nodes, selected pairs of nodes being separated by links ofpredetermined link bandwidth capacities, a plurality of paths connectingat least two of the plurality of nodes, each of said plurality of pathsbeing composed of at least one link, said node comprising: a receiveraccepting a bandwidth reservation request including a requestedbandwidth capacity, an origination point and a destination point; a datastore containing available bandwidth capacity for each link in theethernet network; and a request processor for reserving link capacity ona selected one of the plurality of paths based on said bandwidthreservation request and said available bandwidth capacity for each linkof the chosen one of the plurality of paths.
 8. The node of claim 7wherein said request processor includes: a data store interface foraccessing said data store to determine if the bandwidth capacityavailable for all links in the selected one of the plurality of paths isgreater than the requested bandwidth capacity; and a booking manager forreserving bandwidth for the links of the selected one of the pluralityof paths if the bandwidth reservation request can be satisfied for alllinks in the selected one of the plurality of paths.
 9. The node ofclaim 7 further including a path choosing module for determining theselected one of the plurality of paths based on the origination pointand the destination point in the bandwidth reservation request.
 10. Acomputer readable medium having stored thereon computer executableinstructions for controlling bandwidth resources in an ethernet networkhaving a plurality of nodes, selected pairs of said plurality of nodesbeing separated by links of predetermined link bandwidth capacity, theethernet network having a plurality of paths connecting at least two ofsaid plurality of nodes together, each of said plurality of paths beingcomposed of at least one link, said computer executable instructionscomprising the steps of: receiving a bandwidth reservation requestincluding a requested bandwidth capacity, an origination point and adestination point; storing available bandwidth capacity for each link inthe ethernet network; and reserving link bandwidth capacity for aselected one of the plurality of paths based on said bandwidthreservation request and said available bandwidth capacity for each linkin the chosen one of the plurality of paths.
 11. The computer executableinstructions of claim 10 wherein said step of reserving link bandwidthcapacity includes the steps of: consulting the stored bandwidthinformation to determine if the bandwidth capacity available for alllinks in the selected one of the plurality of paths is greater than therequested bandwidth capacity; and reserving bandwidth for the links ofthe selected one of the plurality of paths if the bandwidth reservationrequest can be satisfied for all links in the selected one of theplurality of paths.
 12. The computer executable instructions of claim 10further including the step of determining the selected one of theplurality of paths based on the origination point and the destinationpoint in the bandwidth reservation request.